Field of the Invention
This invention relates generally to airbags such as used to provide impact protection for an occupant of a motor vehicle and, more particularly, to side airbags including or having an internal diffuser such as particularly suited in or for the protection of a seated vehicle occupant in the event of the occurrence of a side impact or collision.
Discussion of Related Art
Vehicular inflatable restraint systems, e.g., airbag systems, were developed to supplement conventional safety belts by deploying into the space between an occupant and an interior object or surface in the vehicle during a collision event. The airbag acts to decelerate the occupant, thus reducing the possibility of injury to the occupant caused by unintended contact with the interior of the vehicle.
Many typical airbag systems consist of several individual components joined to form an operational module. Such components generally include an airbag, an inflator, a sensor, and an electronic control unit. Airbags are typically constructed or made of a thin, durable fabric or other material that is folded to fit into a compartment of a steering wheel, dashboard, vehicle seat, compartment, roof, roof rail, or other space in or of a vehicle. The airbag inflator is in fluid communication with the airbag cushion, and is configured to supply or produce a gas to inflate the airbag when it is needed. The sensors detect sudden decelerations of the vehicle that are characteristic of an impact. The readings taken by the sensors are processed in the electronic control unit using an algorithm to determine whether a collision has occurred.
Upon detection of an impact of sufficient severity, the control unit sends an electrical signal to the inflator. The inflator using one or more of various technologies, including pyrotechnic compounds and stored pressurized gas, produces, forms or otherwise supplies or provides a volume of an inflation gas. The inflation gas is channeled into the airbag, to inflate the airbag. Inflation of the airbag causes it to deploy, placing it in position to receive the impact of a vehicle occupant. After inflation, the airbag rapidly deflates such as by venting the inflation gas from an opening or openings in the airbag and thus facilitating the occupant to exit the vehicle.
As experience in the manufacture and use of airbags has increased, the engineering challenges involved in their design, construction, and use have become better understood. Inflatable restraint systems typically include devices to protect an occupant in a vehicle by absorbing physical impact resulting upon a vehicle collision using the elasticity of an airbag cushion. Airbag systems can generally be classified into systems such as a driver airbag system, a passenger airbag system, and a side airbag system.
The use of side airbags, also sometimes referred to as side impact airbags, is widespread in present day automotive technology. Typically, a side airbag is stored or located in an inner side structure, such as a pillar of a vehicle or in a backrest of a seat of a vehicle and, in the event of an impact or collision helps to protect an occupant, especially the thorax of an occupant, during a side impact or collision.
In practice, side airbag systems are generally installed to prevent or otherwise minimize or reduce harm to an occupant resulting from colliding with the vehicle side or door as well as to prevent an occupant from being injured by fragments of a broken door window or to prevent an occupant from being expelled from a vehicle body such as, for example, when the occupant is inclined to the door or the door is dented inward upon the side collision of the vehicle.
As will be appreciated, as compared to frontal impacts and frontal airbags, side impacts or collisions such as to cause or produce the deployment of a side airbag typically result in a significantly reduced time period between the occurrence of deployment event, e.g., the vehicle collision or impact, and contact of the occupant with the deployed airbag.
Placement and positioning of the airbags are typically determined based on presumptions made of the position of a vehicle occupant during normal operation of the vehicle. Thus, a vehicle occupant enjoys optimal protection from a specific airbag when the occupant is in the presumed range of positions when the airbag deploys.
In some situations, injuries have been noted to occur when the occupant is “out-of-position” (OOP) with regard to the presumed position discussed above. Further, due to the close positioning to occupants of side airbags and the reduced time period between the occurrence of deployment event and contact of the occupant with a side airbag, the problems of out-of-position occupants can be particularly troublesome in connection with side airbags.
While increasing the volume of the airbag or decreasing the inflator generate load can act to decrease the airbag forces experienced by an OOP occupant, such approaches are generally contrary to the sought objective of providing desired occupant protection in the event of a vehicle impact.
It has been discovered that various parts of the body require different levels of impact protection. For example, a seat mounted side airbag may inflate beside an occupant in a vehicle seat to protect the pelvis and thorax of the occupant against lateral impact. The weight of the occupant may generally tend to slide with the pelvis; hence, it may be beneficial for the pelvic portion of the seat mounted airbag to inflate stiffly to provide comparatively firm protection. By contrast, the thorax is more sensitive and generally carries less mass, and thus should preferably be more softly cushioned during impact to avoid potential injury to an occupant's ribs.
Recently, dual chambered side impact airbags have been developed to provide a pressure differential between the pelvic and thorax portions of a side airbag. These airbags have two separate chambers, one on top of the other. The top chamber is used for providing impact protection for the thorax of an occupant in a seat and the bottom chamber is used to provide impact protection for an occupant's pelvis. In these systems an inflator is placed in a housing that has multiple orifices for channeling inflation gases into both chambers. The pelvic chamber is inflated to a higher pressure than that of the thorax chamber.
As with other types of airbags, thorax/pelvic side airbags must be deployed rapidly in order to be effective. When a vehicle or some other object impacts the side of another vehicle, the side airbag must deploy in a matter of milliseconds. However, the airbag industry has experienced difficulty in deploying the lower pelvic portion of the side airbag in its intended position in a sufficient time period. This is because intrusion into the vehicle compartment generally occurs at or near the pelvic region due to the location of the colliding vehicle's bumper. If the pelvic portion of the side airbag is not positioned before significant intrusion occurs, the deploying side airbag may rebound off the armrest on the vehicle door, or otherwise be prevented from deploying in its proper position, possibly compromising the physical safety of the occupant.
Accordingly, it is desirable to develop a side airbag system that can rapidly and timely position the pelvic portion of the inflatable cushion in its intended position to provide effective impact protection for a passenger. It is further desirable to have an airbag assembly capable of having at least two inflatable portions that are inflated to different pressures while simultaneously maintaining its ability to position itself in a rapid and timely manner. It is also desirable to provide a side impact airbag cushion that is firm enough to prevent strikethrough of the occupant's pelvis while simultaneously being soft enough to provide adequate impact protection while limiting the possibility of being injured by the bag itself.
Thus, with the widespread usage and incorporation of side airbag cushions, there is a growing need and demand for improved side airbag cushion designs and manufacture such as can desirably achieve improved control of inflation gas flow and/or improved control of airbag deployment.